Pulp process



A. HOCHE PULP PROCESS Ojct. 5, 1937.

'File Nov. 2, 1954 M v:Us

mm wmSoE uo Mqlommlwzlg mo .3301 N E. mPSzzz Ov INVENTOR BY 0 f ATTORNEY Patented 0.151937 f PATEN Price PULL PRDCESS Adam Hoche,Brooklyn,` N. Y., assignor to Cellulose Research, Inc., Chicago, Ill., a corporation of Illinois Application November 2, 1934, Serial No. 751,255

1 Claim.

This invention relates to cellulose fibre, particularly \to the separation thereof from bodies consisting largely thereof associated with undesired natural substances.

Those skilled in the art of making cellulose pulp, that is, the separation of cellulose bres from bodies consisting largely thereof associated with undesired or deleterious substances, are fully aware that the present day processes include many steps, which require costly equipment, are slow in operation, and, due to the necessary agitation of the bre and the subjection thereof to powerful chemical substances for protracted periods, result in a pulpor bre` which is both short and weak. A iurther'disadvantage with present processes is the low yield.

Applicant, realizing the'deficiencies in present day processes, after protracted study, experimentation, analysis. and testing arrived at the conclusion `that a proper process for the recovery of cellulose fibres must be one in which the fibre is subjected to the least possible mechanical `agitation or handling; to the lowest possible temperature; treated for the shortest possible time; subjected to a chemical substance or substance most active in action upon the foreign or deleterious qrundesired substances associated with' the bre, and least active or injurious to the fibre itself; and, further, that the process should preferably be such that the number of steps is reduced to a minimum,-preferably substantially one, to the end that separation and bleaching be accomplished in one treatment.

With this end in view, applicant has devised a process for the separation of cellulose bre from associated undesired natural substances which is, in effect, aone step process. This process is carried out without mechanical agitation; at room temperature, save for any increased temperaextremely short exposure of the libre to the chemicals used; includes the use of chemicals `which are extremely active toward the undesired and deleterious substances and comparatively inert, in the concentrations used, toward thev cellulose; and substantially separates the deleterious substances and bleaches in one treatment, which completes the process save for a necessary separation of the chemicals used from the treated material and a subsequent waterwash of the material to remove the last traces of chemicals and soluble impurities from the cellulose pulp.

In the single ligure of the drawing is shown t a ow sheet illustrating in schematic form the various instrumentalitles of the apparatus which ture due to the reacting masses; necessitates anv may be used advantageously in carrying into effect the process of the present invention, together with informative legends as to materials, reagents, temperature and times of operations.

In carrying out the process, applicant selects 5 a suitable cellulose bre carrying mass, such as wood chips, sisal, hemp, bagasse or the like, in` fact any of the ordinary and wellknown source materials. Y

The selected material M is placed in a vessel T 10 of suitable form, size and material and equipped with. theobvious accessories for facilitating the treatment. In general, any vessel of the general iorm of a tank is suitable. The material is preferably placed somewhat loosely in the tank, to 15 the end that the treating solution S may readily penetrate to every particle.

Onto the material in the selected vessel, applicant owsor otherwise suitably distributes the treating solution so that the material is com- 20 pletely covered.

The treating solution consists of water and nitric acid mixed to a concentration of from 40 to Baume. The concentration is varied in accordance with the resistance to treatment of 25 the material and the length of time found most suitable for the particular material, judged from the standpoint of resulting product.

In many cases, especially in the case of bagasse,

saccharoses will be present in sufficient quantity 30 Y to cause the reaction to proceed andl at aproper rate. In many cases, however, in order not only to accelerate the reaction but to produce the proper reaction, ordinary cane-sugar or molasses is added. This sugar or molasses may be added to "i the original water solution of nitric acid or evenly distributed throughout the mass of material to be treated or even roughly thrown into themass, either before or after adding the diluted nitric acid. I add, usually, about 5 pounds of cane 40 sugar, or the equivalent of molasses, to each ton of wood chips, but this may be decreased to about one pound in some cases and in others increased to 8 pounds depending upon the quantity of substances in the fibre mass, capable of reacting 45 n to form oxalic acid, or the rapidity with which I desire the reaction t'o proceed.

The reaction is started at ordinary room temperature, but the mass heats up as the reaction progresses. No pressure is used, and no agitation of the mass.

After about 40 minutes in the case of ordinary materials, using 40'45 Baume acid, the reaction is practically completed, but is is usual and advantageous to allow the reacted mass to stand solution lis separated from the bre.

for about two hours to certainly insure the commass is then washed withwater in any suitable l` or appropriate manner until suitable tests show the material ffree from the undesired substances. When a centrifuge is used to separate the fibre mass from liquids "the washing may take place inA the centrifuge. In any event the washing is continued until by proper and appropriate tests, it is found that the washing has proceeded to the desired extent, as by washing until acid free.

' The yield obtained by the described process is much higher than obtained by the usual processes.

A yie1d ofA 15%' to 20% higher than by usual vprocesses'seems to be usual.

The process is also suitable for treating many forms of source materials which are unsuitable for the ordinary processes. It seems to have a power of disintegration not exhibited by usual processes.

The product resulting from the process is of high quality. The bre is long and strong and usually is ot a whiteness obviating the necessity of a bleach. If a bleach is necessary lit may be applied in the ordinary and well known manner.

The product is especially suitable for the production of cellulose esters. The reason for the superior quality is not thoroughly understood but it is believed to be due to the large percentage of ,V oXy-cellulose present.

The product is ready for the paper mil without further treatment.

The explanation of the reaction which takes place in the process is diiilcult. It is believed that a reaction between the saccharose or starch and perhaps lignin andthe nitric acid generates oxalic acid, andthis oxallc acid, in what might be called the nascent condition, is the active disintegrating agent. At any rate when the mass heats and vapors come ofl', oxalic acid may be detected in the vapors.

'I'he rcost for chemicals islow lbecause of the nitric acid used, pnly about 5% to 10% is consumed by a single treatment of a ilbre bearing mass. The remainder is recovered by, for example, the separation at the centrifuge, and may be used again by bringing it up to proper strength.

'Ihe gist vof the process consists in using dilute acid solution, such as nitric acid, with a substance such as a saccharose or starch or lignin which will by reaction generate oxalic acid, in situ, in a bath which is free from other chemicals which attack the mass so strongly as to injure the iibre.

Having described the principle and mode of operation of my invention and particular application thereof, I desire to have it understood that the mode of operation selected is merely-illustrative and does not exhaust `the possible modes of exhibiting the underlying principle.

What I claim as new and desire to secure by Letters Patent of the United States, is:

The process of separating a bleached cellulose bre from a bre mass admixed with undesired other natural substances with a higher yield of longer fibre 'than known processes which consists in treating said mass for about 40 minutes to 2 hours with about 1 to 8 pounds of a Substance selected from the group comprising cane sugar, starch and molasses to 2000 pounds of said mass and dilute nitric acid of about 40-45 Baume sufilcient to well cover the mass and then separating the solids from the liquids and washing with water until substantially acid free.

ADAM HOCHE. 

